Add explicit heap limiting options to pcre2_match(), with associated features

for listing, configuring, etc.


git-svn-id: svn://vcs.exim.org/pcre2/code/trunk@739 6239d852-aaf2-0410-a92c-79f79f948069

1 files changed, 348 insertions, 340 deletions

diff --git a/doc/pcre2test.txt b/doc/pcre2test.txt
index 9f27861..c311d83 100644
--- a/doc/pcre2test.txt
+++ b/doc/pcre2test.txt
@@ -185,31 +185,37 @@ COMMAND LINE OPTIONS
                  successful  compilation,  each pattern is passed to the just-
                  in-time compiler, if available.
 
+       -jitverify
+                 Behave as if each pattern line has  the  jitverify  modifier;
+                 after  successful  compilation, each pattern is passed to the
+                 just-in-time compiler, if available, and the use  of  JIT  is
+                 verified.
+
        -pattern modifier-list
                  Behave as if each pattern line contains the given modifiers.
 
        -q        Do not output the version number of pcre2test at the start of
                  execution.
 
-       -S size   On  Unix-like  systems, set the size of the run-time stack to
+       -S size   On Unix-like systems, set the size of the run-time  stack  to
                  size megabytes.
 
        -subject modifier-list
                  Behave as if each subject line contains the given modifiers.
 
-       -t        Run each compile and match many times with a timer, and  out-
-                 put  the  resulting  times  per compile or match. When JIT is
-                 used, separate times are given for the  initial  compile  and
-                 the  JIT  compile.  You  can control the number of iterations
-                 that are used for timing by following -t with a number (as  a
-                 separate  item  on  the command line). For example, "-t 1000"
+       -t        Run  each compile and match many times with a timer, and out-
+                 put the resulting times per compile or  match.  When  JIT  is
+                 used,  separate  times  are given for the initial compile and
+                 the JIT compile. You can control  the  number  of  iterations
+                 that  are used for timing by following -t with a number (as a
+                 separate item on the command line). For  example,  "-t  1000"
                  iterates 1000 times. The default is to iterate 500,000 times.
 
        -tm       This is like -t except that it times only the matching phase,
                  not the compile phase.
 
-       -T -TM    These  behave like -t and -tm, but in addition, at the end of
-                 a run, the total times for all compiles and matches are  out-
+       -T -TM    These behave like -t and -tm, but in addition, at the end  of
+                 a  run, the total times for all compiles and matches are out-
                  put.
 
        -version  Output the PCRE2 version number and then exit.
@@ -217,139 +223,139 @@ COMMAND LINE OPTIONS
 
 DESCRIPTION
 
-       If  pcre2test  is given two filename arguments, it reads from the first
+       If pcre2test is given two filename arguments, it reads from  the  first
        and writes to the second. If the first name is "-", input is taken from
-       the  standard  input. If pcre2test is given only one argument, it reads
+       the standard input. If pcre2test is given only one argument,  it  reads
        from that file and writes to stdout. Otherwise, it reads from stdin and
        writes to stdout.
 
-       When  pcre2test  is  built,  a configuration option can specify that it
-       should be linked with the libreadline or libedit library. When this  is
-       done,  if the input is from a terminal, it is read using the readline()
+       When pcre2test is built, a configuration option  can  specify  that  it
+       should  be linked with the libreadline or libedit library. When this is
+       done, if the input is from a terminal, it is read using the  readline()
        function. This provides line-editing and history facilities. The output
        from the -help option states whether or not readline() will be used.
 
-       The  program  handles  any number of tests, each of which consists of a
-       set of input lines. Each set starts with a regular expression  pattern,
+       The program handles any number of tests, each of which  consists  of  a
+       set  of input lines. Each set starts with a regular expression pattern,
        followed by any number of subject lines to be matched against that pat-
        tern. In between sets of test data, command lines that begin with # may
        appear. This file format, with some restrictions, can also be processed
-       by the perltest.sh script that is distributed with PCRE2 as a means  of
+       by  the perltest.sh script that is distributed with PCRE2 as a means of
        checking that the behaviour of PCRE2 and Perl is the same.
 
        When the input is a terminal, pcre2test prompts for each line of input,
-       using "re>" to prompt for regular expression patterns, and  "data>"  to
-       prompt  for subject lines. Command lines starting with # can be entered
+       using  "re>"  to prompt for regular expression patterns, and "data>" to
+       prompt for subject lines. Command lines starting with # can be  entered
        only in response to the "re>" prompt.
 
-       Each subject line is matched separately and independently. If you  want
+       Each  subject line is matched separately and independently. If you want
        to do multi-line matches, you have to use the \n escape sequence (or \r
-       or \r\n, etc., depending on the newline setting) in a  single  line  of
-       input  to encode the newline sequences. There is no limit on the length
-       of subject lines; the input buffer is automatically extended if  it  is
-       too  small.  There  are  replication features that makes it possible to
-       generate long repetitive pattern or subject  lines  without  having  to
+       or  \r\n,  etc.,  depending on the newline setting) in a single line of
+       input to encode the newline sequences. There is no limit on the  length
+       of  subject  lines; the input buffer is automatically extended if it is
+       too small. There are replication features that  makes  it  possible  to
+       generate  long  repetitive  pattern  or subject lines without having to
        supply them explicitly.
 
-       An  empty  line  or  the end of the file signals the end of the subject
-       lines for a test, at which point a  new  pattern  or  command  line  is
+       An empty line or the end of the file signals the  end  of  the  subject
+       lines  for  a  test,  at  which  point a new pattern or command line is
        expected if there is still input to be read.
 
 
 COMMAND LINES
 
-       In  between sets of test data, a line that begins with # is interpreted
+       In between sets of test data, a line that begins with # is  interpreted
        as a command line. If the first character is followed by white space or
-       an  exclamation  mark,  the  line is treated as a comment, and ignored.
+       an exclamation mark, the line is treated as  a  comment,  and  ignored.
        Otherwise, the following commands are recognized:
 
          #forbid_utf
 
-       Subsequent  patterns  automatically  have   the   PCRE2_NEVER_UTF   and
-       PCRE2_NEVER_UCP  options  set, which locks out the use of the PCRE2_UTF
-       and PCRE2_UCP options and the use of (*UTF) and (*UCP) at the start  of
-       patterns.  This  command  also  forces an error if a subsequent pattern
-       contains any occurrences of \P, \p, or \X, which  are  still  supported
-       when  PCRE2_UTF  is not set, but which require Unicode property support
+       Subsequent   patterns   automatically   have  the  PCRE2_NEVER_UTF  and
+       PCRE2_NEVER_UCP options set, which locks out the use of  the  PCRE2_UTF
+       and  PCRE2_UCP options and the use of (*UTF) and (*UCP) at the start of
+       patterns. This command also forces an error  if  a  subsequent  pattern
+       contains  any  occurrences  of \P, \p, or \X, which are still supported
+       when PCRE2_UTF is not set, but which require Unicode  property  support
        to be included in the library.
 
-       This is a trigger guard that is used in test files to ensure  that  UTF
-       or  Unicode property tests are not accidentally added to files that are
-       used when Unicode support is  not  included  in  the  library.  Setting
-       PCRE2_NEVER_UTF  and  PCRE2_NEVER_UCP as a default can also be obtained
-       by the use of #pattern; the difference is that  #forbid_utf  cannot  be
-       unset,  and the automatic options are not displayed in pattern informa-
+       This  is  a trigger guard that is used in test files to ensure that UTF
+       or Unicode property tests are not accidentally added to files that  are
+       used  when  Unicode  support  is  not  included in the library. Setting
+       PCRE2_NEVER_UTF and PCRE2_NEVER_UCP as a default can also  be  obtained
+       by  the  use  of #pattern; the difference is that #forbid_utf cannot be
+       unset, and the automatic options are not displayed in pattern  informa-
        tion, to avoid cluttering up test output.
 
          #load <filename>
 
        This command is used to load a set of precompiled patterns from a file,
-       as  described  in  the  section entitled "Saving and restoring compiled
+       as described in the section entitled  "Saving  and  restoring  compiled
        patterns" below.
 
          #newline_default [<newline-list>]
 
-       When PCRE2 is built, a default newline  convention  can  be  specified.
-       This  determines which characters and/or character pairs are recognized
+       When  PCRE2  is  built,  a default newline convention can be specified.
+       This determines which characters and/or character pairs are  recognized
        as indicating a newline in a pattern or subject string. The default can
-       be  overridden when a pattern is compiled. The standard test files con-
-       tain tests of various newline conventions,  but  the  majority  of  the
-       tests  expect  a  single  linefeed  to  be  recognized  as a newline by
+       be overridden when a pattern is compiled. The standard test files  con-
+       tain  tests  of  various  newline  conventions, but the majority of the
+       tests expect a single  linefeed  to  be  recognized  as  a  newline  by
        default. Without special action the tests would fail when PCRE2 is com-
        piled with either CR or CRLF as the default newline.
 
        The #newline_default command specifies a list of newline types that are
-       acceptable as the default. The types must be one of CR, LF, CRLF,  ANY-
+       acceptable  as the default. The types must be one of CR, LF, CRLF, ANY-
        CRLF, or ANY (in upper or lower case), for example:
 
          #newline_default LF Any anyCRLF
 
        If the default newline is in the list, this command has no effect. Oth-
-       erwise, except when testing the POSIX  API,  a  newline  modifier  that
-       specifies  the  first  newline  convention in the list (LF in the above
-       example) is added to any pattern that does not already have  a  newline
+       erwise,  except  when  testing  the  POSIX API, a newline modifier that
+       specifies the first newline convention in the list  (LF  in  the  above
+       example)  is  added to any pattern that does not already have a newline
        modifier. If the newline list is empty, the feature is turned off. This
        command is present in a number of the standard test input files.
 
-       When the POSIX API is being tested there is  no  way  to  override  the
-       default  newline  convention,  though it is possible to set the newline
-       convention from within the pattern. A warning is  given  if  the  posix
+       When  the  POSIX  API  is  being tested there is no way to override the
+       default newline convention, though it is possible to  set  the  newline
+       convention  from  within  the  pattern. A warning is given if the posix
        modifier is used when #newline_default would set a default for the non-
        POSIX API.
 
          #pattern <modifier-list>
 
-       This command sets a default modifier list that applies  to  all  subse-
+       This  command  sets  a default modifier list that applies to all subse-
        quent patterns. Modifiers on a pattern can change these settings.
 
          #perltest
 
-       The  appearance of this line causes all subsequent modifier settings to
+       The appearance of this line causes all subsequent modifier settings  to
        be checked for compatibility with the perltest.sh script, which is used
-       to  confirm that Perl gives the same results as PCRE2. Also, apart from
-       comment lines, none of the other command lines are  permitted,  because
-       they  and  many  of the modifiers are specific to pcre2test, and should
-       not be used in test files that are also processed by  perltest.sh.  The
-       #perltest  command  helps detect tests that are accidentally put in the
+       to confirm that Perl gives the same results as PCRE2. Also, apart  from
+       comment  lines,  none of the other command lines are permitted, because
+       they and many of the modifiers are specific to  pcre2test,  and  should
+       not  be  used in test files that are also processed by perltest.sh. The
+       #perltest command helps detect tests that are accidentally put  in  the
        wrong file.
 
          #pop [<modifiers>]
          #popcopy [<modifiers>]
 
-       These commands are used to manipulate the stack of  compiled  patterns,
-       as  described  in  the  section entitled "Saving and restoring compiled
+       These  commands  are used to manipulate the stack of compiled patterns,
+       as described in the section entitled  "Saving  and  restoring  compiled
        patterns" below.
 
          #save <filename>
 
-       This command is used to save a set of compiled patterns to a  file,  as
-       described  in  the section entitled "Saving and restoring compiled pat-
+       This  command  is used to save a set of compiled patterns to a file, as
+       described in the section entitled "Saving and restoring  compiled  pat-
        terns" below.
 
          #subject <modifier-list>
 
-       This command sets a default modifier list that applies  to  all  subse-
-       quent  subject lines. Modifiers on a subject line can change these set-
+       This  command  sets  a default modifier list that applies to all subse-
+       quent subject lines. Modifiers on a subject line can change these  set-
        tings.
 
 
@@ -357,58 +363,58 @@ MODIFIER SYNTAX
 
        Modifier lists are used with both pattern and subject lines. Items in a
        list are separated by commas followed by optional white space. Trailing
-       whitespace in a modifier list is ignored. Some modifiers may  be  given
-       for  both patterns and subject lines, whereas others are valid only for
+       whitespace  in  a modifier list is ignored. Some modifiers may be given
+       for both patterns and subject lines, whereas others are valid only  for
        one  or  the  other.  Each  modifier  has  a  long  name,  for  example
-       "anchored",  and  some of them must be followed by an equals sign and a
-       value, for example, "offset=12". Values cannot  contain  comma  charac-
-       ters,  but may contain spaces. Modifiers that do not take values may be
+       "anchored", and some of them must be followed by an equals sign  and  a
+       value,  for  example,  "offset=12". Values cannot contain comma charac-
+       ters, but may contain spaces. Modifiers that do not take values may  be
        preceded by a minus sign to turn off a previous setting.
 
        A few of the more common modifiers can also be specified as single let-
-       ters,  for  example "i" for "caseless". In documentation, following the
+       ters, for example "i" for "caseless". In documentation,  following  the
        Perl convention, these are written with a slash ("the /i modifier") for
-       clarity.  Abbreviated  modifiers  must all be concatenated in the first
-       item of a modifier list. If the first item is not recognized as a  long
-       modifier  name, it is interpreted as a sequence of these abbreviations.
+       clarity. Abbreviated modifiers must all be concatenated  in  the  first
+       item  of a modifier list. If the first item is not recognized as a long
+       modifier name, it is interpreted as a sequence of these  abbreviations.
        For example:
 
          /abc/ig,newline=cr,jit=3
 
-       This is a pattern line whose modifier list starts with  two  one-letter
-       modifiers  (/i  and  /g).  The lower-case abbreviated modifiers are the
+       This  is  a pattern line whose modifier list starts with two one-letter
+       modifiers (/i and /g). The lower-case  abbreviated  modifiers  are  the
        same as used in Perl.
 
 
 PATTERN SYNTAX
 
-       A pattern line must start with one of the following characters  (common
+       A  pattern line must start with one of the following characters (common
        symbols, excluding pattern meta-characters):
 
          / ! " ' ` - = _ : ; , % & @ ~
 
-       This  is  interpreted  as the pattern's delimiter. A regular expression
-       may be continued over several input lines, in which  case  the  newline
+       This is interpreted as the pattern's delimiter.  A  regular  expression
+       may  be  continued  over several input lines, in which case the newline
        characters are included within it. It is possible to include the delim-
        iter within the pattern by escaping it with a backslash, for example
 
          /abc\/def/
 
-       If you do this, the escape and the delimiter form part of the  pattern,
+       If  you do this, the escape and the delimiter form part of the pattern,
        but since the delimiters are all non-alphanumeric, this does not affect
-       its interpretation. If the terminating delimiter  is  immediately  fol-
+       its  interpretation.  If  the terminating delimiter is immediately fol-
        lowed by a backslash, for example,
 
          /abc/\
 
-       then  a  backslash  is added to the end of the pattern. This is done to
-       provide a way of testing the error condition that arises if  a  pattern
+       then a backslash is added to the end of the pattern. This  is  done  to
+       provide  a  way of testing the error condition that arises if a pattern
        finishes with a backslash, because
 
          /abc\/
 
-       is  interpreted as the first line of a pattern that starts with "abc/",
-       causing pcre2test to read the next line as a continuation of the  regu-
+       is interpreted as the first line of a pattern that starts with  "abc/",
+       causing  pcre2test to read the next line as a continuation of the regu-
        lar expression.
 
        A pattern can be followed by a modifier list (details below).
@@ -416,7 +422,7 @@ PATTERN SYNTAX
 
 SUBJECT LINE SYNTAX
 
-       Before    each   subject   line   is   passed   to   pcre2_match()   or
+       Before   each   subject   line   is   passed   to   pcre2_match()    or
        pcre2_dfa_match(), leading and trailing white space is removed, and the
        line is scanned for backslash escapes. The following provide a means of
        encoding non-printing characters in a visible way:
@@ -436,23 +442,23 @@ SUBJECT LINE SYNTAX
          \x{hh...}  hexadecimal character (any number of hex digits)
 
        The use of \x{hh...} is not dependent on the use of the utf modifier on
-       the  pattern. It is recognized always. There may be any number of hexa-
-       decimal digits inside the braces; invalid  values  provoke  error  mes-
+       the pattern. It is recognized always. There may be any number of  hexa-
+       decimal  digits  inside  the  braces; invalid values provoke error mes-
        sages.
 
-       Note  that  \xhh  specifies one byte rather than one character in UTF-8
-       mode; this makes it possible to construct invalid UTF-8  sequences  for
-       testing  purposes.  On the other hand, \x{hh} is interpreted as a UTF-8
-       character in UTF-8 mode, generating more than one byte if the value  is
-       greater  than  127.   When testing the 8-bit library not in UTF-8 mode,
+       Note that \xhh specifies one byte rather than one  character  in  UTF-8
+       mode;  this  makes it possible to construct invalid UTF-8 sequences for
+       testing purposes. On the other hand, \x{hh} is interpreted as  a  UTF-8
+       character  in UTF-8 mode, generating more than one byte if the value is
+       greater than 127.  When testing the 8-bit library not  in  UTF-8  mode,
        \x{hh} generates one byte for values less than 256, and causes an error
        for greater values.
 
        In UTF-16 mode, all 4-digit \x{hhhh} values are accepted. This makes it
        possible to construct invalid UTF-16 sequences for testing purposes.
 
-       In UTF-32 mode, all 4- to 8-digit \x{...}  values  are  accepted.  This
-       makes  it  possible  to  construct invalid UTF-32 sequences for testing
+       In  UTF-32  mode,  all  4- to 8-digit \x{...} values are accepted. This
+       makes it possible to construct invalid  UTF-32  sequences  for  testing
        purposes.
 
        There is a special backslash sequence that specifies replication of one
@@ -460,45 +466,45 @@ SUBJECT LINE SYNTAX
 
          \[<characters>]{<count>}
 
-       This  makes  it possible to test long strings without having to provide
+       This makes it possible to test long strings without having  to  provide
        them as part of the file. For example:
 
          \[abc]{4}
 
-       is converted to "abcabcabcabc". This feature does not support  nesting.
+       is  converted to "abcabcabcabc". This feature does not support nesting.
        To include a closing square bracket in the characters, code it as \x5D.
 
-       A  backslash  followed  by  an equals sign marks the end of the subject
+       A backslash followed by an equals sign marks the  end  of  the  subject
        string and the start of a modifier list. For example:
 
          abc\=notbol,notempty
 
-       If the subject string is empty and \= is followed  by  whitespace,  the
-       line  is  treated  as a comment line, and is not used for matching. For
+       If  the  subject  string is empty and \= is followed by whitespace, the
+       line is treated as a comment line, and is not used  for  matching.  For
        example:
 
          \= This is a comment.
          abc\= This is an invalid modifier list.
 
-       A backslash followed  by  any  other  non-alphanumeric  character  just
+       A  backslash  followed  by  any  other  non-alphanumeric character just
        escapes that character. A backslash followed by anything else causes an
-       error. However, if the very last character in the line is  a  backslash
-       (and  there  is  no  modifier list), it is ignored. This gives a way of
-       passing an empty line as data, since a real empty line  terminates  the
+       error.  However,  if the very last character in the line is a backslash
+       (and there is no modifier list), it is ignored. This  gives  a  way  of
+       passing  an  empty line as data, since a real empty line terminates the
        data input.
 
 
 PATTERN MODIFIERS
 
-       There  are  several types of modifier that can appear in pattern lines.
+       There are several types of modifier that can appear in  pattern  lines.
        Except where noted below, they may also be used in #pattern commands. A
-       pattern's  modifier  list can add to or override default modifiers that
+       pattern's modifier list can add to or override default  modifiers  that
        were set by a previous #pattern command.
 
    Setting compilation options
 
-       The following modifiers set options for pcre2_compile(). The most  com-
-       mon  ones have single-letter abbreviations. See pcre2api for a descrip-
+       The  following modifiers set options for pcre2_compile(). The most com-
+       mon ones have single-letter abbreviations. See pcre2api for a  descrip-
        tion of their effects.
 
              allow_empty_class         set PCRE2_ALLOW_EMPTY_CLASS
@@ -530,15 +536,15 @@ PATTERN MODIFIERS
              utf                       set PCRE2_UTF
 
        As well as turning on the PCRE2_UTF option, the utf modifier causes all
-       non-printing  characters  in  output  strings  to  be printed using the
-       \x{hh...} notation. Otherwise, those less than 0x100 are output in  hex
-       without  the  curly brackets. Setting utf in 16-bit or 32-bit mode also
-       causes pattern and subject  strings  to  be  translated  to  UTF-16  or
+       non-printing characters in output  strings  to  be  printed  using  the
+       \x{hh...}  notation. Otherwise, those less than 0x100 are output in hex
+       without the curly brackets. Setting utf in 16-bit or 32-bit  mode  also
+       causes  pattern  and  subject  strings  to  be  translated to UTF-16 or
        UTF-32, respectively, before being passed to library functions.
 
    Setting compilation controls
 
-       The  following  modifiers  affect  the  compilation  process or request
+       The following modifiers  affect  the  compilation  process  or  request
        information about the pattern:
 
              bsr=[anycrlf|unicode]     specify \R handling
@@ -571,34 +577,34 @@ PATTERN MODIFIERS
 
    Newline and \R handling
 
-       The bsr modifier specifies what \R in a pattern should match. If it  is
-       set  to  "anycrlf",  \R  matches  CR, LF, or CRLF only. If it is set to
-       "unicode", \R matches any Unicode  newline  sequence.  The  default  is
+       The  bsr modifier specifies what \R in a pattern should match. If it is
+       set to "anycrlf", \R matches CR, LF, or CRLF only.  If  it  is  set  to
+       "unicode",  \R  matches  any  Unicode  newline sequence. The default is
        specified when PCRE2 is built, with the default default being Unicode.
 
-       The  newline  modifier specifies which characters are to be interpreted
+       The newline modifier specifies which characters are to  be  interpreted
        as newlines, both in the pattern and in subject lines. The type must be
        one of CR, LF, CRLF, ANYCRLF, or ANY (in upper or lower case).
 
    Information about a pattern
 
-       The  debug modifier is a shorthand for info,fullbincode, requesting all
+       The debug modifier is a shorthand for info,fullbincode, requesting  all
        available information.
 
        The bincode modifier causes a representation of the compiled code to be
-       output  after compilation. This information does not contain length and
+       output after compilation. This information does not contain length  and
        offset values, which ensures that the same output is generated for dif-
-       ferent  internal  link  sizes  and different code unit widths. By using
-       bincode, the same regression tests can be used  in  different  environ-
+       ferent internal link sizes and different code  unit  widths.  By  using
+       bincode,  the  same  regression tests can be used in different environ-
        ments.
 
-       The  fullbincode  modifier, by contrast, does include length and offset
-       values. This is used in a few special tests that run only for  specific
+       The fullbincode modifier, by contrast, does include length  and  offset
+       values.  This is used in a few special tests that run only for specific
        code unit widths and link sizes, and is also useful for one-off tests.
 
-       The  info  modifier  requests  information  about  the compiled pattern
-       (whether it is anchored, has a fixed first character, and so  on).  The
-       information  is  obtained  from the pcre2_pattern_info() function. Here
+       The info modifier  requests  information  about  the  compiled  pattern
+       (whether  it  is anchored, has a fixed first character, and so on). The
+       information is obtained from the  pcre2_pattern_info()  function.  Here
        are some typical examples:
 
            re> /(?i)(^a|^b)/m,info
@@ -616,118 +622,118 @@ PATTERN MODIFIERS
          Last code unit = 'c' (caseless)
          Subject length lower bound = 3
 
-       "Compile options" are those specified by modifiers;  "overall  options"
-       have  added options that are taken or deduced from the pattern. If both
-       sets of options are the same, just a single "options" line  is  output;
-       if  there  are  no  options,  the line is omitted. "First code unit" is
-       where any match must start; if there is more than one they  are  listed
-       as  "starting  code  units".  "Last code unit" is the last literal code
-       unit that must be present in any match. This  is  not  necessarily  the
-       last  character.  These lines are omitted if no starting or ending code
+       "Compile  options"  are those specified by modifiers; "overall options"
+       have added options that are taken or deduced from the pattern. If  both
+       sets  of  options are the same, just a single "options" line is output;
+       if there are no options, the line is  omitted.  "First  code  unit"  is
+       where  any  match must start; if there is more than one they are listed
+       as "starting code units". "Last code unit" is  the  last  literal  code
+       unit  that  must  be  present in any match. This is not necessarily the
+       last character. These lines are omitted if no starting or  ending  code
        units are recorded.
 
-       The framesize modifier shows the size, in bytes, of the storage  frames
-       used  by  pcre2_match()  for handling backtracking. The size depends on
+       The  framesize modifier shows the size, in bytes, of the storage frames
+       used by pcre2_match() for handling backtracking. The  size  depends  on
        the number of capturing parentheses in the pattern.
 
-       The callout_info modifier requests information about all  the  callouts
+       The  callout_info  modifier requests information about all the callouts
        in the pattern. A list of them is output at the end of any other infor-
        mation that is requested. For each callout, either its number or string
        is given, followed by the item that follows it in the pattern.
 
    Passing a NULL context
 
-       Normally,  pcre2test  passes a context block to pcre2_compile(). If the
-       null_context modifier is set, however, NULL  is  passed.  This  is  for
-       testing  that  pcre2_compile()  behaves correctly in this case (it uses
+       Normally, pcre2test passes a context block to pcre2_compile().  If  the
+       null_context  modifier  is  set,  however,  NULL is passed. This is for
+       testing that pcre2_compile() behaves correctly in this  case  (it  uses
        default values).
 
    Specifying the pattern's length
 
        By default, patterns are passed to the compiling functions as zero-ter-
-       minated  strings.  When  using the POSIX wrapper API, there is no other
-       option. However, when using PCRE2's native API, patterns can be  passed
-       by  length  instead  of  being zero-terminated. The use_length modifier
-       causes this to happen.  Using a length happens  automatically  (whether
-       or  not  use_length is set) when hex is set, because patterns specified
+       minated strings. When using the POSIX wrapper API, there  is  no  other
+       option.  However, when using PCRE2's native API, patterns can be passed
+       by length instead of being  zero-terminated.  The  use_length  modifier
+       causes  this  to happen.  Using a length happens automatically (whether
+       or not use_length is set) when hex is set, because  patterns  specified
        in hexadecimal may contain binary zeros.
 
    Specifying pattern characters in hexadecimal
 
-       The hex modifier specifies that the characters of the  pattern,  except
-       for  substrings  enclosed  in single or double quotes, are to be inter-
-       preted as pairs of hexadecimal digits. This feature is  provided  as  a
+       The  hex  modifier specifies that the characters of the pattern, except
+       for substrings enclosed in single or double quotes, are  to  be  inter-
+       preted  as  pairs  of hexadecimal digits. This feature is provided as a
        way of creating patterns that contain binary zeros and other non-print-
-       ing characters. White space is permitted between pairs of  digits.  For
+       ing  characters.  White space is permitted between pairs of digits. For
        example, this pattern contains three characters:
 
          /ab 32 59/hex
 
-       Parts  of  such  a  pattern are taken literally if quoted. This pattern
-       contains nine characters, only two of which are specified in  hexadeci-
+       Parts of such a pattern are taken literally  if  quoted.  This  pattern
+       contains  nine characters, only two of which are specified in hexadeci-
        mal:
 
          /ab "literal" 32/hex
 
-       Either  single or double quotes may be used. There is no way of includ-
-       ing the delimiter within a substring. The hex and expand modifiers  are
+       Either single or double quotes may be used. There is no way of  includ-
+       ing  the delimiter within a substring. The hex and expand modifiers are
        mutually exclusive.
 
-       The  POSIX  API  cannot  be used with patterns specified in hexadecimal
+       The POSIX API cannot be used with  patterns  specified  in  hexadecimal
        because they may contain binary zeros, which conflicts with regcomp()'s
-       requirement  for  a  zero-terminated  string.  Such patterns are always
+       requirement for a zero-terminated  string.  Such  patterns  are  always
        passed to pcre2_compile() as a string with a length, not as zero-termi-
        nated.
 
    Specifying wide characters in 16-bit and 32-bit modes
 
        In 16-bit and 32-bit modes, all input is automatically treated as UTF-8
-       and translated to UTF-16 or UTF-32 when the utf modifier  is  set.  For
+       and  translated  to  UTF-16 or UTF-32 when the utf modifier is set. For
        testing the 16-bit and 32-bit libraries in non-UTF mode, the utf8_input
-       modifier can be used. It is mutually exclusive with  utf.  Input  lines
+       modifier  can  be  used. It is mutually exclusive with utf. Input lines
        are interpreted as UTF-8 as a means of specifying wide characters. More
        details are given in "Input encoding" above.
 
    Generating long repetitive patterns
 
-       Some tests use long patterns that are very repetitive. Instead of  cre-
-       ating  a very long input line for such a pattern, you can use a special
-       repetition feature, similar to the  one  described  for  subject  lines
-       above.  If  the  expand  modifier is present on a pattern, parts of the
+       Some  tests use long patterns that are very repetitive. Instead of cre-
+       ating a very long input line for such a pattern, you can use a  special
+       repetition  feature,  similar  to  the  one described for subject lines
+       above. If the expand modifier is present on a  pattern,  parts  of  the
        pattern that have the form
 
          \[<characters>]{<count>}
 
        are expanded before the pattern is passed to pcre2_compile(). For exam-
        ple, \[AB]{6000} is expanded to "ABAB..." 6000 times. This construction
-       cannot be nested. An initial "\[" sequence is recognized only  if  "]{"
-       followed  by  decimal  digits and "}" is found later in the pattern. If
+       cannot  be  nested. An initial "\[" sequence is recognized only if "]{"
+       followed by decimal digits and "}" is found later in  the  pattern.  If
        not, the characters remain in the pattern unaltered. The expand and hex
        modifiers are mutually exclusive.
 
-       If  part  of an expanded pattern looks like an expansion, but is really
+       If part of an expanded pattern looks like an expansion, but  is  really
        part of the actual pattern, unwanted expansion can be avoided by giving
        two values in the quantifier. For example, \[AB]{6000,6000} is not rec-
        ognized as an expansion item.
 
-       If the info modifier is set on an expanded pattern, the result  of  the
+       If  the  info modifier is set on an expanded pattern, the result of the
        expansion is included in the information that is output.
 
    JIT compilation
 
-       Just-in-time  (JIT)  compiling  is  a heavyweight optimization that can
-       greatly speed up pattern matching. See the pcre2jit  documentation  for
-       details.  JIT  compiling  happens, optionally, after a pattern has been
-       successfully compiled into an internal form. The JIT compiler  converts
+       Just-in-time (JIT) compiling is a  heavyweight  optimization  that  can
+       greatly  speed  up pattern matching. See the pcre2jit documentation for
+       details. JIT compiling happens, optionally, after a  pattern  has  been
+       successfully  compiled into an internal form. The JIT compiler converts
        this to optimized machine code. It needs to know whether the match-time
        options PCRE2_PARTIAL_HARD and PCRE2_PARTIAL_SOFT are going to be used,
-       because  different  code  is generated for the different cases. See the
-       partial modifier in "Subject Modifiers" below for details of how  these
+       because different code is generated for the different  cases.  See  the
+       partial  modifier in "Subject Modifiers" below for details of how these
        options are specified for each match attempt.
 
-       JIT  compilation  is  requested by the /jit pattern modifier, which may
+       JIT compilation is requested by the /jit pattern  modifier,  which  may
        optionally be followed by an equals sign and a number in the range 0 to
-       7.   The  three bits that make up the number specify which of the three
+       7.  The three bits that make up the number specify which of  the  three
        JIT operating modes are to be compiled:
 
          1  compile JIT code for non-partial matching
@@ -744,31 +750,31 @@ PATTERN MODIFIERS
          6  soft and hard partial matching only
          7  all three modes
 
-       If no number is given, 7 is  assumed.  The  phrase  "partial  matching"
+       If  no  number  is  given,  7 is assumed. The phrase "partial matching"
        means a call to pcre2_match() with either the PCRE2_PARTIAL_SOFT or the
-       PCRE2_PARTIAL_HARD option set. Note that such a call may return a  com-
+       PCRE2_PARTIAL_HARD  option set. Note that such a call may return a com-
        plete match; the options enable the possibility of a partial match, but
-       do not require it. Note also that if you request JIT  compilation  only
-       for  partial  matching (for example, /jit=2) but do not set the partial
-       modifier on a subject line, that match will not use  JIT  code  because
+       do  not  require it. Note also that if you request JIT compilation only
+       for partial matching (for example, /jit=2) but do not set  the  partial
+       modifier  on  a  subject line, that match will not use JIT code because
        none was compiled for non-partial matching.
 
-       If  JIT compilation is successful, the compiled JIT code will automati-
-       cally be used when an appropriate type of match  is  run,  except  when
-       incompatible  run-time options are specified. For more details, see the
-       pcre2jit documentation. See also the jitstack modifier below for a  way
+       If JIT compilation is successful, the compiled JIT code will  automati-
+       cally  be  used  when  an appropriate type of match is run, except when
+       incompatible run-time options are specified. For more details, see  the
+       pcre2jit  documentation. See also the jitstack modifier below for a way
        of setting the size of the JIT stack.
 
-       If  the  jitfast  modifier is specified, matching is done using the JIT
-       "fast path" interface, pcre2_jit_match(), which skips some of the  san-
-       ity  checks that are done by pcre2_match(), and of course does not work
-       when JIT is not supported. If jitfast is specified without  jit,  jit=7
+       If the jitfast modifier is specified, matching is done  using  the  JIT
+       "fast  path" interface, pcre2_jit_match(), which skips some of the san-
+       ity checks that are done by pcre2_match(), and of course does not  work
+       when  JIT  is not supported. If jitfast is specified without jit, jit=7
        is assumed.
 
-       If  the jitverify modifier is specified, information about the compiled
-       pattern shows whether JIT compilation was or  was  not  successful.  If
-       jitverify  is  specified without jit, jit=7 is assumed. If JIT compila-
-       tion is successful when jitverify is set, the text "(JIT)" is added  to
+       If the jitverify modifier is specified, information about the  compiled
+       pattern  shows  whether  JIT  compilation was or was not successful. If
+       jitverify is specified without jit, jit=7 is assumed. If  JIT  compila-
+       tion  is successful when jitverify is set, the text "(JIT)" is added to
        the first output line after a match or non match when JIT-compiled code
        was actually used in the match.
 
@@ -779,19 +785,19 @@ PATTERN MODIFIERS
          /pattern/locale=fr_FR
 
        The given locale is set, pcre2_maketables() is called to build a set of
-       character  tables for the locale, and this is then passed to pcre2_com-
-       pile() when compiling the regular expression. The same tables are  used
-       when  matching the following subject lines. The locale modifier applies
+       character tables for the locale, and this is then passed to  pcre2_com-
+       pile()  when compiling the regular expression. The same tables are used
+       when matching the following subject lines. The locale modifier  applies
        only to the pattern on which it appears, but can be given in a #pattern
-       command  if a default is needed. Setting a locale and alternate charac-
+       command if a default is needed. Setting a locale and alternate  charac-
        ter tables are mutually exclusive.
 
    Showing pattern memory
 
        The memory modifier causes the size in bytes of the memory used to hold
-       the  compiled  pattern  to be output. This does not include the size of
-       the pcre2_code block; it is just the actual compiled data. If the  pat-
-       tern  is  subsequently  passed to the JIT compiler, the size of the JIT
+       the compiled pattern to be output. This does not include  the  size  of
+       the  pcre2_code block; it is just the actual compiled data. If the pat-
+       tern is subsequently passed to the JIT compiler, the size  of  the  JIT
        compiled code is also output. Here is an example:
 
            re> /a(b)c/jit,memory
@@ -801,27 +807,27 @@ PATTERN MODIFIERS
 
    Limiting nested parentheses
 
-       The parens_nest_limit modifier sets a limit  on  the  depth  of  nested
-       parentheses  in  a  pattern.  Breaching  the limit causes a compilation
-       error.  The default for the library is set when  PCRE2  is  built,  but
-       pcre2test  sets  its  own default of 220, which is required for running
+       The  parens_nest_limit  modifier  sets  a  limit on the depth of nested
+       parentheses in a pattern. Breaching  the  limit  causes  a  compilation
+       error.   The  default  for  the library is set when PCRE2 is built, but
+       pcre2test sets its own default of 220, which is  required  for  running
        the standard test suite.
 
    Limiting the pattern length
 
-       The max_pattern_length modifier sets a limit, in  code  units,  to  the
+       The  max_pattern_length  modifier  sets  a limit, in code units, to the
        length of pattern that pcre2_compile() will accept. Breaching the limit
-       causes a compilation  error.  The  default  is  the  largest  number  a
+       causes  a  compilation  error.  The  default  is  the  largest number a
        PCRE2_SIZE variable can hold (essentially unlimited).
 
    Using the POSIX wrapper API
 
-       The  /posix and posix_nosub modifiers cause pcre2test to call PCRE2 via
-       the POSIX wrapper API rather than its native API. When  posix_nosub  is
-       used,  the  POSIX  option  REG_NOSUB  is passed to regcomp(). The POSIX
-       wrapper supports only the 8-bit library. Note that it  does  not  imply
+       The /posix and posix_nosub modifiers cause pcre2test to call PCRE2  via
+       the  POSIX  wrapper API rather than its native API. When posix_nosub is
+       used, the POSIX option REG_NOSUB is  passed  to  regcomp().  The  POSIX
+       wrapper  supports  only  the 8-bit library. Note that it does not imply
        POSIX matching semantics; for more detail see the pcre2posix documenta-
-       tion. The following pattern modifiers set  options  for  the  regcomp()
+       tion.  The  following  pattern  modifiers set options for the regcomp()
        function:
 
          caseless           REG_ICASE
@@ -831,35 +837,35 @@ PATTERN MODIFIERS
          ucp                REG_UCP        )   the POSIX standard
          utf                REG_UTF8       )
 
-       The  regerror_buffsize  modifier  specifies a size for the error buffer
-       that is passed to regerror() in the event of a compilation  error.  For
+       The regerror_buffsize modifier specifies a size for  the  error  buffer
+       that  is  passed to regerror() in the event of a compilation error. For
        example:
 
          /abc/posix,regerror_buffsize=20
 
-       This  provides  a means of testing the behaviour of regerror() when the
-       buffer is too small for the error message. If  this  modifier  has  not
+       This provides a means of testing the behaviour of regerror()  when  the
+       buffer  is  too  small  for the error message. If this modifier has not
        been set, a large buffer is used.
 
-       The  aftertext  and  allaftertext  subject  modifiers work as described
-       below. All other modifiers are either ignored, with a warning  message,
+       The aftertext and allaftertext  subject  modifiers  work  as  described
+       below.  All other modifiers are either ignored, with a warning message,
        or cause an error.
 
    Testing the stack guard feature
 
-       The  stackguard  modifier  is  used  to  test the use of pcre2_set_com-
-       pile_recursion_guard(), a function that is  provided  to  enable  stack
-       availability  to  be checked during compilation (see the pcre2api docu-
-       mentation for details). If the number  specified  by  the  modifier  is
+       The stackguard modifier is used  to  test  the  use  of  pcre2_set_com-
+       pile_recursion_guard(),  a  function  that  is provided to enable stack
+       availability to be checked during compilation (see the  pcre2api  docu-
+       mentation  for  details).  If  the  number specified by the modifier is
        greater than zero, pcre2_set_compile_recursion_guard() is called to set
-       up callback from pcre2_compile() to a local function. The  argument  it
-       receives  is  the current nesting parenthesis depth; if this is greater
+       up  callback  from pcre2_compile() to a local function. The argument it
+       receives is the current nesting parenthesis depth; if this  is  greater
        than the value given by the modifier, non-zero is returned, causing the
        compilation to be aborted.
 
    Using alternative character tables
 
-       The  value  specified for the tables modifier must be one of the digits
+       The value specified for the tables modifier must be one of  the  digits
        0, 1, or 2. It causes a specific set of built-in character tables to be
        passed to pcre2_compile(). This is used in the PCRE2 tests to check be-
        haviour with different character tables. The digit specifies the tables
@@ -870,15 +876,15 @@ PATTERN MODIFIERS
                pcre2_chartables.c.dist
          2   a set of tables defining ISO 8859 characters
 
-       In  table 2, some characters whose codes are greater than 128 are iden-
-       tified as letters, digits, spaces,  etc.  Setting  alternate  character
+       In table 2, some characters whose codes are greater than 128 are  iden-
+       tified  as  letters,  digits,  spaces, etc. Setting alternate character
        tables and a locale are mutually exclusive.
 
    Setting certain match controls
 
        The following modifiers are really subject modifiers, and are described
-       below.  However, they may be included in a pattern's modifier list,  in
-       which  case  they  are  applied to every subject line that is processed
+       below.   However, they may be included in a pattern's modifier list, in
+       which case they are applied to every subject  line  that  is  processed
        with that pattern. They may not appear in #pattern commands. These mod-
        ifiers do not affect the compilation process.
 
@@ -895,24 +901,24 @@ PATTERN MODIFIERS
              substitute_unknown_unset   use PCRE2_SUBSTITUTE_UNKNOWN_UNSET
              substitute_unset_empty     use PCRE2_SUBSTITUTE_UNSET_EMPTY
 
-       These  modifiers may not appear in a #pattern command. If you want them
+       These modifiers may not appear in a #pattern command. If you want  them
        as defaults, set them in a #subject command.
 
    Saving a compiled pattern
 
-       When a pattern with the push modifier is successfully compiled,  it  is
-       pushed  onto  a  stack  of compiled patterns, and pcre2test expects the
-       next line to contain a new pattern (or a command) instead of a  subject
+       When  a  pattern with the push modifier is successfully compiled, it is
+       pushed onto a stack of compiled patterns,  and  pcre2test  expects  the
+       next  line to contain a new pattern (or a command) instead of a subject
        line. This facility is used when saving compiled patterns to a file, as
-       described in the section entitled "Saving and restoring  compiled  pat-
-       terns"  below.  If pushcopy is used instead of push, a copy of the com-
-       piled pattern is stacked, leaving the original  as  current,  ready  to
-       match  the  following  input  lines. This provides a way of testing the
-       pcre2_code_copy() function.   The  push  and  pushcopy   modifiers  are
-       incompatible  with  compilation  modifiers  such  as global that act at
-       match time. Any that are specified are ignored (for the stacked  copy),
+       described  in  the section entitled "Saving and restoring compiled pat-
+       terns" below. If pushcopy is used instead of push, a copy of  the  com-
+       piled  pattern  is  stacked,  leaving the original as current, ready to
+       match the following input lines. This provides a  way  of  testing  the
+       pcre2_code_copy()  function.   The  push  and  pushcopy   modifiers are
+       incompatible with compilation modifiers such  as  global  that  act  at
+       match  time. Any that are specified are ignored (for the stacked copy),
        with a warning message, except for replace, which causes an error. Note
-       that jitverify, which is allowed, does not carry through to any  subse-
+       that  jitverify, which is allowed, does not carry through to any subse-
        quent matching that uses a stacked pattern.
 
 
@@ -923,7 +929,7 @@ SUBJECT MODIFIERS
 
    Setting match options
 
-       The   following   modifiers   set   options   for   pcre2_match()    or
+       The    following   modifiers   set   options   for   pcre2_match()   or
        pcre2_dfa_match(). See pcreapi for a description of their effects.
 
              anchored                  set PCRE2_ANCHORED
@@ -939,20 +945,20 @@ SUBJECT MODIFIERS
              partial_hard (or ph)      set PCRE2_PARTIAL_HARD
              partial_soft (or ps)      set PCRE2_PARTIAL_SOFT
 
-       The  partial matching modifiers are provided with abbreviations because
+       The partial matching modifiers are provided with abbreviations  because
        they appear frequently in tests.
 
-       If the posix modifier was present on the  pattern,  causing  the  POSIX
+       If  the  posix  modifier  was present on the pattern, causing the POSIX
        wrapper API to be used, the only option-setting modifiers that have any
-       effect  are  notbol,  notempty,   and   noteol,   causing   REG_NOTBOL,
-       REG_NOTEMPTY,  and REG_NOTEOL, respectively, to be passed to regexec().
+       effect   are   notbol,   notempty,   and  noteol,  causing  REG_NOTBOL,
+       REG_NOTEMPTY, and REG_NOTEOL, respectively, to be passed to  regexec().
        The other modifiers are ignored, with a warning message.
 
    Setting match controls
 
-       The following modifiers affect the matching process  or  request  addi-
-       tional  information.  Some  of  them may also be specified on a pattern
-       line (see above), in which case they apply to every subject  line  that
+       The  following  modifiers  affect the matching process or request addi-
+       tional information. Some of them may also be  specified  on  a  pattern
+       line  (see  above), in which case they apply to every subject line that
        is matched against that pattern.
 
              aftertext                  show text after match
@@ -972,6 +978,7 @@ SUBJECT MODIFIERS
              get=<number or name>       extract captured substring
              getall                     extract all captured substrings
          /g  global                     global matching
+             heap_limit=<n>             set a limit on heap memory
              jitstack=<n>               set size of JIT stack
              mark                       show mark values
              match_limit=<n>            set a match limit
@@ -991,29 +998,29 @@ SUBJECT MODIFIERS
              zero_terminate             pass the subject as zero-terminated
 
        The effects of these modifiers are described in the following sections.
-       When matching via the POSIX wrapper API, the  aftertext,  allaftertext,
-       and  ovector subject modifiers work as described below. All other modi-
+       When  matching  via the POSIX wrapper API, the aftertext, allaftertext,
+       and ovector subject modifiers work as described below. All other  modi-
        fiers are either ignored, with a warning message, or cause an error.
 
    Showing more text
 
-       The aftertext modifier requests that as well as outputting the part  of
+       The  aftertext modifier requests that as well as outputting the part of
        the subject string that matched the entire pattern, pcre2test should in
        addition output the remainder of the subject string. This is useful for
        tests where the subject contains multiple copies of the same substring.
-       The allaftertext modifier requests the same action  for  captured  sub-
+       The  allaftertext  modifier  requests the same action for captured sub-
        strings as well as the main matched substring. In each case the remain-
        der is output on the following line with a plus character following the
        capture number.
 
-       The  allusedtext modifier requests that all the text that was consulted
-       during a successful pattern match by the interpreter should  be  shown.
-       This  feature  is not supported for JIT matching, and if requested with
-       JIT it is ignored (with  a  warning  message).  Setting  this  modifier
+       The allusedtext modifier requests that all the text that was  consulted
+       during  a  successful pattern match by the interpreter should be shown.
+       This feature is not supported for JIT matching, and if  requested  with
+       JIT  it  is  ignored  (with  a  warning message). Setting this modifier
        affects the output if there is a lookbehind at the start of a match, or
-       a lookahead at the end, or if \K is used  in  the  pattern.  Characters
-       that  precede or follow the start and end of the actual match are indi-
-       cated in the output by '<' or '>' characters underneath them.  Here  is
+       a  lookahead  at  the  end, or if \K is used in the pattern. Characters
+       that precede or follow the start and end of the actual match are  indi-
+       cated  in  the output by '<' or '>' characters underneath them. Here is
        an example:
 
            re> /(?<=pqr)abc(?=xyz)/
@@ -1021,16 +1028,16 @@ SUBJECT MODIFIERS
           0: pqrabcxyz
              <<<   >>>
 
-       This  shows  that  the  matched string is "abc", with the preceding and
-       following strings "pqr" and "xyz"  having  been  consulted  during  the
+       This shows that the matched string is "abc",  with  the  preceding  and
+       following  strings  "pqr"  and  "xyz"  having been consulted during the
        match (when processing the assertions).
 
-       The  startchar  modifier  requests  that the starting character for the
-       match be indicated, if it is different to  the  start  of  the  matched
+       The startchar modifier requests that the  starting  character  for  the
+       match  be  indicated,  if  it  is different to the start of the matched
        string. The only time when this occurs is when \K has been processed as
        part of the match. In this situation, the output for the matched string
-       is  displayed  from  the  starting  character instead of from the match
-       point, with circumflex characters under  the  earlier  characters.  For
+       is displayed from the starting character  instead  of  from  the  match
+       point,  with  circumflex  characters  under the earlier characters. For
        example:
 
            re> /abc\Kxyz/
@@ -1038,7 +1045,7 @@ SUBJECT MODIFIERS
           0: abcxyz
              ^^^
 
-       Unlike  allusedtext, the startchar modifier can be used with JIT.  How-
+       Unlike allusedtext, the startchar modifier can be used with JIT.   How-
        ever, these two modifiers are mutually exclusive.
 
    Showing the value of all capture groups
@@ -1046,98 +1053,98 @@ SUBJECT MODIFIERS
        The allcaptures modifier requests that the values of all potential cap-
        tured parentheses be output after a match. By default, only those up to
        the highest one actually used in the match are output (corresponding to
-       the  return  code from pcre2_match()). Groups that did not take part in
-       the match are output as "<unset>". This modifier is  not  relevant  for
-       DFA  matching  (which does no capturing); it is ignored, with a warning
+       the return code from pcre2_match()). Groups that did not take  part  in
+       the  match  are  output as "<unset>". This modifier is not relevant for
+       DFA matching (which does no capturing); it is ignored, with  a  warning
        message, if present.
 
    Testing callouts
 
-       A callout function is supplied when pcre2test calls the library  match-
-       ing  functions, unless callout_none is specified. If callout_capture is
-       set, the current captured groups are output when a callout occurs.  The
+       A  callout function is supplied when pcre2test calls the library match-
+       ing functions, unless callout_none is specified. If callout_capture  is
+       set,  the current captured groups are output when a callout occurs. The
        default return from the callout function is zero, which allows matching
        to continue.
 
-       The callout_fail modifier can be given one or two numbers. If there  is
-       only  one number, 1 is returned instead of 0 (causing matching to back-
-       track) when a callout  of  that  number  is  reached.  If  two  numbers
-       (<n>:<m>)  are  given,  1  is  returned when callout <n> is reached and
-       there have been at least <m> callouts. The  callout_error  modifier  is
-       similar,  except  that  PCRE2_ERROR_CALLOUT  is  returned,  causing the
-       entire matching process to be aborted. If both these modifiers are  set
+       The  callout_fail modifier can be given one or two numbers. If there is
+       only one number, 1 is returned instead of 0 (causing matching to  back-
+       track)  when  a  callout  of  that  number  is  reached. If two numbers
+       (<n>:<m>) are given, 1 is returned when  callout  <n>  is  reached  and
+       there  have  been  at least <m> callouts. The callout_error modifier is
+       similar, except  that  PCRE2_ERROR_CALLOUT  is  returned,  causing  the
+       entire  matching process to be aborted. If both these modifiers are set
        for the same callout number, callout_error takes precedence.
 
-       Note  that  callouts  with string arguments are always given the number
+       Note that callouts with string arguments are always  given  the  number
        zero. See "Callouts" below for a description of the output when a call-
        out it taken.
 
-       The  callout_data  modifier can be given an unsigned or a negative num-
-       ber.  This is set as the "user data" that is  passed  to  the  matching
-       function,  and  passed  back  when the callout function is invoked. Any
-       value other than zero is used as  a  return  from  pcre2test's  callout
+       The callout_data modifier can be given an unsigned or a  negative  num-
+       ber.   This  is  set  as the "user data" that is passed to the matching
+       function, and passed back when the callout  function  is  invoked.  Any
+       value  other  than  zero  is  used as a return from pcre2test's callout
        function.
 
    Finding all matches in a string
 
        Searching for all possible matches within a subject can be requested by
-       the global or altglobal modifier. After finding a match,  the  matching
-       function  is  called  again to search the remainder of the subject. The
-       difference between global and altglobal is that  the  former  uses  the
-       start_offset  argument  to  pcre2_match() or pcre2_dfa_match() to start
-       searching at a new point within the entire string (which is  what  Perl
+       the  global  or altglobal modifier. After finding a match, the matching
+       function is called again to search the remainder of  the  subject.  The
+       difference  between  global  and  altglobal is that the former uses the
+       start_offset argument to pcre2_match() or  pcre2_dfa_match()  to  start
+       searching  at  a new point within the entire string (which is what Perl
        does), whereas the latter passes over a shortened subject. This makes a
        difference to the matching process if the pattern begins with a lookbe-
        hind assertion (including \b or \B).
 
-       If  an  empty  string  is  matched,  the  next  match  is done with the
+       If an empty string  is  matched,  the  next  match  is  done  with  the
        PCRE2_NOTEMPTY_ATSTART and PCRE2_ANCHORED flags set, in order to search
        for another, non-empty, match at the same point in the subject. If this
-       match fails, the start offset is advanced,  and  the  normal  match  is
-       retried.  This  imitates the way Perl handles such cases when using the
-       /g modifier or the split() function.  Normally,  the  start  offset  is
-       advanced  by  one  character,  but if the newline convention recognizes
-       CRLF as a newline, and the current character is CR followed by  LF,  an
+       match  fails,  the  start  offset  is advanced, and the normal match is
+       retried. This imitates the way Perl handles such cases when  using  the
+       /g  modifier  or  the  split()  function. Normally, the start offset is
+       advanced by one character, but if  the  newline  convention  recognizes
+       CRLF  as  a newline, and the current character is CR followed by LF, an
        advance of two characters occurs.
 
    Testing substring extraction functions
 
-       The  copy  and  get  modifiers  can  be  used  to  test  the pcre2_sub-
+       The copy  and  get  modifiers  can  be  used  to  test  the  pcre2_sub-
        string_copy_xxx() and pcre2_substring_get_xxx() functions.  They can be
-       given  more than once, and each can specify a group name or number, for
+       given more than once, and each can specify a group name or number,  for
        example:
 
           abcd\=copy=1,copy=3,get=G1
 
-       If the #subject command is used to set default copy and/or  get  lists,
-       these  can  be unset by specifying a negative number to cancel all num-
+       If  the  #subject command is used to set default copy and/or get lists,
+       these can be unset by specifying a negative number to cancel  all  num-
        bered groups and an empty name to cancel all named groups.
 
-       The getall modifier tests  pcre2_substring_list_get(),  which  extracts
+       The  getall  modifier  tests pcre2_substring_list_get(), which extracts
        all captured substrings.
 
-       If  the  subject line is successfully matched, the substrings extracted
-       by the convenience functions are output with  C,  G,  or  L  after  the
-       string  number  instead  of  a colon. This is in addition to the normal
-       full list. The string length (that is, the return from  the  extraction
+       If the subject line is successfully matched, the  substrings  extracted
+       by  the  convenience  functions  are  output  with C, G, or L after the
+       string number instead of a colon. This is in  addition  to  the  normal
+       full  list.  The string length (that is, the return from the extraction
        function) is given in parentheses after each substring, followed by the
        name when the extraction was by name.
 
    Testing the substitution function
 
-       If the replace modifier is  set,  the  pcre2_substitute()  function  is
-       called  instead of one of the matching functions. Note that replacement
-       strings cannot contain commas, because a comma signifies the end  of  a
+       If  the  replace  modifier  is  set, the pcre2_substitute() function is
+       called instead of one of the matching functions. Note that  replacement
+       strings  cannot  contain commas, because a comma signifies the end of a
        modifier. This is not thought to be an issue in a test program.
 
-       Unlike  subject strings, pcre2test does not process replacement strings
-       for escape sequences. In UTF mode, a replacement string is  checked  to
-       see  if it is a valid UTF-8 string. If so, it is correctly converted to
-       a UTF string of the appropriate code unit width. If it is not  a  valid
-       UTF-8  string, the individual code units are copied directly. This pro-
+       Unlike subject strings, pcre2test does not process replacement  strings
+       for  escape  sequences. In UTF mode, a replacement string is checked to
+       see if it is a valid UTF-8 string. If so, it is correctly converted  to
+       a  UTF  string of the appropriate code unit width. If it is not a valid
+       UTF-8 string, the individual code units are copied directly. This  pro-
        vides a means of passing an invalid UTF-8 string for testing purposes.
 
-       The following modifiers set options (in additional to the normal  match
+       The  following modifiers set options (in additional to the normal match
        options) for pcre2_substitute():
 
          global                      PCRE2_SUBSTITUTE_GLOBAL
@@ -1147,8 +1154,8 @@ SUBJECT MODIFIERS
          substitute_unset_empty      PCRE2_SUBSTITUTE_UNSET_EMPTY
 
 
-       After  a  successful  substitution, the modified string is output, pre-
-       ceded by the number of replacements. This may be zero if there were  no
+       After a successful substitution, the modified string  is  output,  pre-
+       ceded  by the number of replacements. This may be zero if there were no
        matches. Here is a simple example of a substitution test:
 
          /abc/replace=xxx
@@ -1157,12 +1164,12 @@ SUBJECT MODIFIERS
              =abc=abc=\=global
           2: =xxx=xxx=
 
-       Subject  and replacement strings should be kept relatively short (fewer
-       than 256 characters) for substitution tests, as fixed-size buffers  are
-       used.  To  make it easy to test for buffer overflow, if the replacement
-       string starts with a number in square brackets, that number  is  passed
-       to  pcre2_substitute()  as  the  size  of  the  output buffer, with the
-       replacement string starting at the next character. Here is  an  example
+       Subject and replacement strings should be kept relatively short  (fewer
+       than  256 characters) for substitution tests, as fixed-size buffers are
+       used. To make it easy to test for buffer overflow, if  the  replacement
+       string  starts  with a number in square brackets, that number is passed
+       to pcre2_substitute() as the  size  of  the  output  buffer,  with  the
+       replacement  string  starting at the next character. Here is an example
        that tests the edge case:
 
          /abc/
@@ -1171,11 +1178,11 @@ SUBJECT MODIFIERS
              123abc123\=replace=[9]XYZ
          Failed: error -47: no more memory
 
-       The    default    action    of    pcre2_substitute()   is   to   return
-       PCRE2_ERROR_NOMEMORY when the output buffer is too small.  However,  if
-       the  PCRE2_SUBSTITUTE_OVERFLOW_LENGTH  option is set (by using the sub-
-       stitute_overflow_length modifier), pcre2_substitute() continues  to  go
-       through  the  motions of matching and substituting, in order to compute
+       The   default   action   of    pcre2_substitute()    is    to    return
+       PCRE2_ERROR_NOMEMORY  when  the output buffer is too small. However, if
+       the PCRE2_SUBSTITUTE_OVERFLOW_LENGTH option is set (by using  the  sub-
+       stitute_overflow_length  modifier),  pcre2_substitute() continues to go
+       through the motions of matching and substituting, in order  to  compute
        the size of buffer that is required. When this happens, pcre2test shows
        the required buffer length (which includes space for the trailing zero)
        as part of the error message. For example:
@@ -1185,30 +1192,31 @@ SUBJECT MODIFIERS
          Failed: error -47: no more memory: 10 code units are needed
 
        A replacement string is ignored with POSIX and DFA matching. Specifying
-       partial  matching  provokes  an  error return ("bad option value") from
+       partial matching provokes an error return  ("bad  option  value")  from
        pcre2_substitute().
 
    Setting the JIT stack size
 
-       The jitstack modifier provides a way of setting the maximum stack  size
-       that  is  used  by the just-in-time optimization code. It is ignored if
+       The  jitstack modifier provides a way of setting the maximum stack size
+       that is used by the just-in-time optimization code. It  is  ignored  if
        JIT optimization is not being used. The value is a number of kilobytes.
        Providing a stack that is larger than the default 32K is necessary only
        for very complicated patterns.
 
-   Setting match and depth limits
+   Setting heap, match, and depth limits
 
-       The match_limit and depth_limit modifiers set the appropriate limits in
-       the  match context. These values are ignored when the find_limits modi-
-       fier is specified.
+       The  heap_limit,  match_limit, and depth_limit modifiers set the appro-
+       priate limits in the match context. These values are ignored  when  the
+       find_limits modifier is specified.
 
    Finding minimum limits
 
-       If the find_limits modifier is present on  a  subject  line,  pcre2test
-       calls  the  relevant matching function several times, setting different
-       values  in   the   match   context   via   pcre2_set_match_limit()   or
-       pcre2_set_depth_limit()  until  it  finds  the  minimum values for each
-       parameter that allows the match to complete without error.
+       If  the  find_limits  modifier  is present on a subject line, pcre2test
+       calls the relevant matching function several times,  setting  different
+       values    in    the    match    context   via   pcre2_set_heap_limit(),
+       pcre2_set_match_limit(), or pcre2_set_depth_limit() until it finds  the
+       minimum  values  for  each  parameter that allows the match to complete
+       without error.
 
        If JIT is being used, only the match limit is relevant. If DFA matching
        is being used, only the depth limit is relevant.
@@ -1220,8 +1228,8 @@ SUBJECT MODIFIERS
        quickly with increasing length of subject string.
 
        For  non-DFA  matching,  the minimum depth_limit number is a measure of
-       how much memory for recording backtracking points is needed to complete
-       the  match  attempt.  In the case of DFA matching, depth_limit controls
+       how much nested backtracking happens (that is, how deeply the pattern's
+       tree  is  searched).  In the case of DFA matching, depth_limit controls
        the depth of recursive calls of the internal function that is used  for
        handling pattern recursion, lookaround assertions, and atomic groups.
 
@@ -1632,5 +1640,5 @@ AUTHOR
 
 REVISION
 
-       Last updated: 04 April 2017
+       Last updated: 11 April 2017
        Copyright (c) 1997-2017 University of Cambridge.